Published August 27, 2020 as 10.3174/ajnr.A6726

ORIGINAL RESEARCH PEDIATRICS

Expanding the Neuroimaging Phenotype of Neuronal Ceroid Lipofuscinoses

A. Biswas, P. Krishnan, A. Amirabadi, S. Blaser, S. Mercimek-Andrews, and M. Shroff

ABSTRACT BACKGROUND AND PURPOSE: Neuronal ceroid lipofuscinoses are a group of neurodegenerative disorders characterized by the accumulation of autofluorescent lipopigments in neuronal cells. As a result of storage material in the brain and retina, clinical mani- festations include speech delay, cognitive dysfunction, motor regression, epilepsy, vision loss, and early death. At present, 14 differ- ent ceroid lipofuscinosis (CLN) are known. Recently, the FDA approved the use of recombinant human proenzyme of tripeptidyl-peptidase 1 for CLN2 disease, while phase I/IIa clinical trials for therapy in CLN3 and CLN6 are ongoing. Early diag- nosis is, therefore, key to initiating treatment and arresting disease progression. Neuroimaging features of CLN1, CLN2, CLN3, and CLN5 diseases are well-described, with sparse literature on other subtypes. We aimed to investigate and expand the MR imaging features of genetically proved neuronal ceroid lipofuscinoses subtypes at our institution and also to report the time interval between the age of disease onset and the diagnosis of neuronal ceroid lipofuscinoses.

MATERIALS AND METHODS: We investigated and analyzed the age of disease onset and neuroimaging findings (signal intensity in periventricular, deep, and subcortical white matter, thalami, basal ganglia, posterior limb of the internal capsule, insular/subinsular regions, and ventral pons; and the presence or absence of supratentorial and/or infratentorial atrophy) of patients with genetically proved neuronal ceroid lipofuscinoses at our institution. This group consisted of 24 patients who underwent 40 brain MR imaging investigations between 1993 and 2019, with a male preponderance (male/female ratio ¼ 15:9).

RESULTS: Themeanagesofdiseaseonset,first brain MR imaging, and diagnosis of neuronal ceroid lipofuscinoses were 4.70 6 3.48 years, 6.76 6 4.49 years, and 7.27 6 4.78 years, respectively. Findings on initial brain MR imaging included T2/FLAIR hypointensity in the thalami (n ¼ 22); T2/FLAIR hyperintensity in the periventricular and deep white matter (n ¼ 22), posterior limb of the internal capsule (n ¼ 22), ventral pons (n ¼ 19), and insular/subinsular region (n ¼ 18); supratentorial (n ¼ 21) and infratentorial atrophy (n ¼ 20). Eight of 9 patients who had follow-up neuroimaging showed progressive changes.

CONCLUSIONS: We identified reported classic neuroimaging features in all except 1 patient with neuronal ceroid lipofuscinoses in our study. CLN2, CLN5, and CLN7 diseases showed predominant cerebellar-over-cerebral atrophy. We demonstrate that abnormal signal intensity in the deep white matter, posterior limb of the internal capsule, and ventral pons is more common than previously reported in the literature. We report abnormal signal intensity in the insular/subinsular region for the first time. The difference in the median time from disease onset and diagnosis was 1.5 years.

ABBREVIATIONS: CLN ¼ ceroid lipofuscinosis; DWM ¼ deep white matter; IQR ¼ interquartile range; I-SI ¼ insular/subinsular region; NCL ¼ neuronal ce- roid lipofuscinoses; PLIC ¼ posterior limb of the internal capsule; PVWM ¼ periventricular white matter; SCWM ¼ subcortical white matter

euronal ceroid lipofuscinoses (NCL) are a group of clinically the most common neurodegenerative disorders of childhood, Nand genetically heterogeneous lysosomal storage disorders with an estimated incidence of 1.6–2.4/100,000 in the United characterized by the accumulation of autofluorescent lipopig- States, 2.2/100,000 in Sweden, 2–2.5/100,000 in Denmark, 3.9/ ments in neuronal cells of the brain and retina.1 They constitute 100,000 in Norway, 4.8/100,000 in Finland, and 7/100,000 in Iceland.1,2 Clinical manifestations include speech delay, cognitive Received May 2, 2020; accepted after revision June 16. From the Department of Diagnostic Imaging (A.B., P.K., A.A., S.B., M.S.), The Hospital for Sick Children, Toronto, Canada; Division of Clinical and Metabolic Genetics Please address correspondence to Asthik Biswas, MD, MBBS, Department of (S.M.-A.), Department of Pediatrics, University of Toronto, The Hospital for Sick Diagnostic Imaging, The Hospital for Sick Children, 555 University Ave, Toronto, Children, Toronto, Canada. ON, M5G 1X8, Canada; e-mail: asthik.biswas@sickkids; [email protected]; Previously presented in poster format at: Annual Meeting of the American Society @stikkman11 of Pediatric Neuroradiology, January 10–12, 2020; Miami Beach, Florida. http://dx.doi.org/10.3174/ajnr.A6726

AJNR Am J Neuroradiol :2020 www.ajnr.org 1

Copyright 2020 by American Society of Neuroradiology. Table 1: Subgroups of NCL, their genes, names, and MIM numbers diseases,20-25 with scarce literature on Locus Name Gene Symbol Protein Name MIM Number other subtypes.26-31 Given the rapidly CLN1 PPT1 Palmitoyl protein thioesterase 1 600722 changing landscape in cell biology and CLN2 TPP1 Tripeptidyl peptidase 1 607998 translation in NCL and the need for CLN3 CLN3 CLN3 607042 CLN4 DNAJC5 DnaJ homolog 611203 early diagnosis facilitating early treat- CLN5 CLN5 CLN5 608102 ment, we performed a retrospective CLN6 CLN6 CLN6 601780 review study to investigate and expand CLN7 MFSD8 Major facilitator superfamily 611124 the MR imaging features of the disease CLN8 CLN8 CLN8 607837 CLN9 N/A Unknown 609055 in patients with genetically confirmed CLN10 CTSD Cathepsin D 116840 NCL diagnosed at our institution. We CLN11 GRN Granulins 138945 also report the time interval between CLN12 ATP13A2 Probable cation transporting 610513 the age of disease onset, first brain MR CLN13 CTSF Cathepsin F 603539 imaging, and diagnosis in this study. CLN14 KCTD7 BTB/POZ domain-containing 611725 Note:—MIM indicates Mendelian Inheritance in Man; N/A, not applicable. MATERIALS AND METHODS The institutional Research Ethics Board approved the study (REB 1000065260). Patients were identified from a pre- vious study data base.32 Patient demographics and clinical features were obtained through electronic chart review. Brain MR imaging examinations were reviewed for quality and co-read by 2 of the authors (A.B. and P.K.) with consensus review. Specifically, the nature of T2 signal intensity in the thalami, periven- tricular white matter (PVWM), deep white matter (DWM), subcortical white matter (SCWM), basal ganglia, FIG 1. Time delay between disease onset (median, 3.6 years; IQR, 3 years) and clinical, radiologic, posterior limb of the internal capsule and histopathologic diagnoses (median, 5.1 years; IQR, 6.7 years) of NCL is depicted. (PLIC), insular/subinsular region (I- SI), and ventral pons, along with the presence or absence of supratentorial dysfunction, developmental regression, epilepsy, vision loss, and and infratentorial atrophy, was documented. Atrophy was graded 3 early death. Although traditionally classified on the basis of the subjectively as mild, moderate, and severe. Note was made of the age of onset (infantile, late-infantile, juvenile, and adult), classifi- degree of cerebral atrophy relative to cerebellar atrophy. cation is now based on genetic etiology, with 14 different ceroid Volumetric analysis was not performed due to insufficient numbers lipofuscinosis (CLN) genes known at present (Table 1).4 Several of cases with volume data. The age of disease onset was determined new insights into the cell biology of NCL have emerged,5-7 with by documented history in the hospital records system (Chartmaxx; ongoing translational research likely to have therapeutic implica- https://chartmaxx.software.informer.com/). A working diagnosis of tions.8 Furthermore, it has been proposed that the different sub- NCL was defined either by a histopathologic basis with positive types of NCL are actually distinct disorders, each with a unique conjunctival or skin biopsy demonstrating curvilinear profiles, fin- underlying molecular pathomechanism sharing a common end gerprint profiles, or granular osmiophilic profiles; or by a clinicora- point in the form of neuronal loss and autofluorescent storage ma- diologic basis when clinical presentation or family history, or both terial.8 Recently, the FDA approved the use of cerliponase alfa in conjunction with MR imaging findings were highly suggestive of (Brineura), a recombinant human proenzyme of tripeptidyl-pepti- the diagnosis. All patients in the cohort eventually had confirmed dase 1, for CLN2 disease.9 The treatment arrests disease progres- genetic diagnoses via direct Sanger testing, the details of which have 32 sion; therefore, early diagnosis is essential for optimal treatment been published previously. Data were entered into Excel outcomes. In addition, phase I/IIa clinical trials with gene therapy (Microsoft). Data were analyzed with descriptive statistics (median are currently in progress for CLN310 and CLN6 diseases.11 and interquartile range [IQR] for age calculated in Excel). The classic neuroimaging features in brain MR imaging of NCL reported in the literature include T2-hypointense thalami, RESULTS T2-hyperintense periventricular white matter, and progressive Thirty-four patients with genetically confirmed neuronal ceroid cerebral and cerebellar volume loss.12-19 Subtype-specific imaging lipofuscinosis were identified between 1993 and 2019. Most of findings are well-described in CLN1, CLN2, CLN3, and CLN5 these patients and their molecular genetic investigations have

2 Biswas 2020 www.ajnr.org Table 2: Clinical features of patients with NCLa Speech Visual Behavioral Cognitive Delay Impairment Seizures Abnormalities Decline Developmental NCL Subtypes Sex n (%) n (%) n (%) n (%) n (%) Regression n (%) CLN1 disease (n ¼ 6) M (n ¼ 4), F (n ¼ 2) 5 (83) 5 (83) 4 (67) 3 (50) 5 (83) 5 (83) CLN2 disease (n ¼ 5) M (n ¼ 5) 4 (80) 3 (60) 4 (80) 2 (40) 4 (80) 4 (80) CLN3 disease (n ¼ 2) M (n ¼ 2) 2 (100) 2 (100) 1 (50) 2 (100) 2 (100) 2 (100) CLN5 disease (n ¼ 1) F (n ¼ 1) 1 (100) 1 (100) 1 (100) 1 (100) 1 (100) 1 (100) CLN6 disease (n ¼ 2) M (n ¼ 1), F (n ¼ 1) 1 (50) 1 (50) 1 (50) 1 (50) 2 (100) 2 (100) CLN7 disease (n ¼ 6) M (n ¼ 4), F (n ¼ 2) 6 (100) 2 (33) 6 (100) 2 (33) 6 (100) 6 (100) CLN8 disease (n ¼ 2) M (n ¼ 1), F (n ¼ 1) 2 (100) 0 (0) 2 (100) 0 (0) 2 (100) 2 (100) a Data are number of patients (percentage in parenthesis).

Table 3: Brain MR imaging features of patients with NCL T2 Hyperintensity n (%) Volume Loss n (%) STWM (PVWM and/or T2 hypointense Corpus DWM and/or SCWM Insular/Sub- NCL Subtypes thalami n (%) Striatum and/or PLIC) Insular Pons Supratentorial Cerebellar CLN1 disease (n ¼ 6) 6 (100) 6 (100) 6 (100) 4 (67) 6 (100) 6 (100) 6 (100) CLN2 disease (n ¼ 5) 5 (100) 3 (60) 5 (100) 4 (80) 3 (60) 4 (80) 4 (80) CLN3 disease (n ¼ 2) 0 (0) 0 (0) 1 (50) 1 (50) 0 (0) 2 (100) 0 (0) CLN5 disease (n ¼ 1) 1 (100) 1 (100) 1 (100) 1 (100) 1 (100) 1 (100) 1 (100) CLN6 disease (n ¼ 2) 2 (100) 1 (50) 2 (100) 1 (50) 2 (100) 1 (50) 1 (50) CLN7 disease (n ¼ 6) 6 (100) 2 (33) 6 (100) 5 (83) 5 (83) 5 (83) 6 (100) CLN8 disease (n ¼ 2) 2 (100) 2 (100) 2 (100) 2 (100) 2 (100) 2 (100) 2 (100) Note:—STWM indicates supratentorial white matter. been reported.32 Of these, 24 patients (male/female ratio = 15:9) patient showed abnormality in the SCWM. Four patients demon- had 40 MR imaging examinations and were therefore included in strated T2/FLAIR hyperintensity in the I-SI region. All patients the study. The time delay between disease onset and diagnoses is showed supratentorial atrophy (mild ¼ 2; moderate ¼ 2; severe ¼ depicted in Fig 1. The median (IQR) age of disease onset, first 2) and cerebellar atrophy (mild ¼ 4; moderate ¼ 2), with 5 patients brain MR imaging, and age of genetic diagnoses were 3.6 (3.0), showing brain stem atrophy. In all 6 patients, the degree of cerebral 4.9 (5.4), and 5.1 (6.7) years, respectively (Fig 1). The NCL sub- atrophywasgreaterthanthatofcerebellaratrophy. types were CLN1 (n ¼ 6), CLN2 (n ¼ 5), CLN3 (n ¼ 2), CLN5 Three of 6 patients had follow-up imaging. All 3 patients dem- (n ¼ 1), CLN6 (n ¼ 2), CLN7 (n ¼ 6), and CLN8 (n ¼ 2) diseases. onstrated progressive supratentorial and cerebellar volume loss, The most common symptom was developmental and cognitive and 2 patients showed progressive white matter T2/FLAIR hyper- regression (n ¼ 22). Other presenting symptoms included speech intensity now extending to involve the SCWM. delay (n ¼ 21), seizures (n ¼ 19), impaired vision (n ¼ 14), and behavioral abnormalities (n ¼ 11). Clinical features and their dis- CLN2 Disease tribution to each subgroup of NCL are listed in Table 2. In CLN2 disease (n ¼ 5), the median (IQR) age of onset was 3.5 Brain MR imaging features are summarized in Table 3.Findings (5.3) years. The median (IQR) age the first MR imaging was 8.7 on initial brain MR imaging included the following: 1) T2/FLAIR (8.4) years. All patients (n ¼ 5) showed T2/FLAIR hypointensity hypointensity in the thalami (n ¼ 22); 2) T2/FLAIR hyperintensity in the thalami, whereas 3 patients showed T2 hyperintensity in inthePVWMandDWM(n ¼ 22); 3) T2/FLAIR hyperintensity in basal ganglia. All patients showed T2/FLAIR hyperintensity in the PLIC (n ¼ 22); 4) T2/FLAIR hyperintensity in the ventral pons the PLIC, PVWM, and DWM, with 1 patient demonstrating ab- (n ¼ 19); 5) T2/FLAIR hyperintensity in the I-SI region (n ¼ 18); 6) normality involving the SCWM. Four patients showed T2/FLAIR supratentorial atrophy (n ¼ 21; mild, [n ¼ 10]; moderate-severe, hyperintensity in the I-SI region, and 3 showed signal abnormal- [n ¼ 11]; and 7) cerebellar atrophy [n ¼ 20]).Eightof9patients ity in the pons. who had follow-up neuroimaging showed progressive changes. Four patients showed supratentorial atrophy (mild ¼ 1; Imaging findings in each subtype are summarized below. moderate ¼ 1; severe ¼ 2) and cerebellar atrophy (mild ¼ 2; severe ¼ 2), with 4 patients showing brain stem atrophy. In 3 CLN1 Disease of 5 patients, cerebellar atrophy was greater than cerebral In CLN1 disease (n ¼ 6), the median (IQR) age of onset was 3 atrophy. (8.5) years, while the median (IQR) age at first MR imaging was Three patients had follow-up imaging. All 3 showed progres- 3.5 (11.5) years. On the initial MR imaging, all patients (n ¼ 6) sive supratentorial atrophy, and 2 showed progression in cerebel- showed T2/FLAIR hypointensity in the thalami and T2 hyperin- lar atrophy. One patient who had normal signal in the I-SI region tensity in the basal ganglia. All patients had T2/FLAIR hyperin- and pons on the initial MR imaging showed signal abnormality tensity in the PVWM, DWM, PLIC, and pons, while only 1 in both regions on follow-up MR imaging.

AJNR Am J Neuroradiol :2020 www.ajnr.org 3 CLN6 Disease In CLN6 disease (n ¼ 2), the age at disease onset was 4 years in a female and 9 years in a male patient. MR imaging of both patients (6A and 6B, at 8.6 years and 10.8 years of age) showed T2/FLAIR hypointense thal- ami, and both showed T2/FLAIR hyperintense signal in the PLIC, PVWM, DWM, and pons (none in the SCWM). One (patient 6A) had T2/FLAIR hyperintensity in the basal FIG 2. A 4-year-old boy with CLN2 disease. Axial FLAIR MR imaging shows hypointense thalami ganglia. Patient 6A showed severe su- and hyperintense insular/subinsular region and posterior limb of the internal capsule (A); hyperin- pratentorial and cerebellar atrophy and tense periventricular and deep white matter (B), and hyperintense ventral pons (C). Note diffuse cerebral and cerebellar volume loss (A–C). brain stem atrophy. Patient 6B did not have atrophy on the initial MR imaging but showed mild supratentorial atrophy on follow-up imaging after 4.5 years. Both patients showed a greater degree of cerebral atrophy compared with cere- bellar atrophy.

CLN7 Disease In CLN7 disease (n ¼ 6), the median age of onset of disease was 3.75 years (IQR, 3.1 years), while the median age at first MR imaging was 4.5 years (IQR, 4 years). All patients showed FIG 3. Progression of CLN2 disease. Coronal T2-weighted MR imaging at 6 years of age (A)shows T2/FLAIR hypointense thalami; 2 no discernible volume loss. Follow-up MR imaging at 11 and 13 years of age (B and C) shows pro- showed a T2/FLAIR hyperintense ba- gressive cerebral and cerebellar volume loss. Note the greater degree of cerebellar volume loss sal ganglia; all showed T2/FLAIR relative to the cerebrum. hyperintense PLIC, PVWM, and DWM (none in the SCWM) and 5 showed abnormal signal in the I-SI Sample cases of CLN2 disease are shown in Figs 2 and 3. region and pons. Five patients showed supratentorial atrophy (mild ¼ 3; moderate ¼ 2), while all 6 patients showed cerebellar atrophy (mild ¼ 1; moderate ¼ 4; severe ¼ 1). Four patients had CLN3 Disease brain stem atrophy. In 5 of 6 patients, the degree of cerebellar In CLN3 disease (n ¼ 2), the age of onset was 10 years in patient atrophy was greater than cerebral atrophy (Fig 4), with equal at- 3A and was unknown in patient 3B. MR imaging of patient 3A rophy in 1 patient. None of the patients had follow-up MR performed at 6 years of age showed no signal abnormality or vol- imaging. ume loss on the initial MR imaging. Follow-up MR imaging at 10 years of age showed supratentorial volume loss with PVWM CLN8 Disease and DWM signal abnormality. MR imaging of patient 3B per- In CLN8 disease (n ¼ 2), the age of disease onset was 3.7 years in formed at 1.2 years of age showed only mild supratentorial atro- a male (8A) and 3.3 years in a female (8B) patient. MR imaging of phy without signal change and no obvious progression on follow- both patients (at 4.5 and 3.3 years, respectively) showed T2/ up imaging after 6 years (the first MR imaging for patient 3B was FLAIR hypointense thalami and T2/FLAIR hyperintense basal actually performed for follow-up of intraventricular hemorrhage; ganglia, PVWM, DWM, PLIC, I-SI region, and pons. None had therefore, the atrophy was possibly not related to NCL). Neither SCWM signal abnormality. Both showed supratentorial (mild ¼ patient had cerebellar atrophy. 1; moderate ¼ 1) and cerebellar (mild ¼ 1, moderate ¼ 1) atro- phy. Patient 8A had greater cerebellar atrophy compared with CLN5 Disease cerebral atrophy while patient 8B had an equal degree of atrophy. In CLN5 disease (n ¼ 1), the disease onset was at 3.5 years of age. Neither of the patients had follow-up MR imaging. MR imaging at 6.5 years of age showed T2/FLAIR hypointense thal- ami; and T2/FLAIR hyperintensity in basal ganglia, PVWM, DWM, DISCUSSION PLIC, I-SI region, and pons, along with mild supratentorial and We report 24 patients with genetically confirmed NCL and their severe cerebellar atrophy. There was no follow-up MR imaging. brain MR imaging features, which is one of the largest patient

4 Biswas 2020 www.ajnr.org FIG 4. CLN7 disease. Coronal T2-weighted MR imaging of 4 different patients (A, B, C,andE) and coronal reformatted CT of 1 patient (D). Note cerebellar more than cerebral volume loss in all patients. cohorts, to the best of our knowledge. Brain MR imaging findings decreased volume of the dorsomedial thalami and corona radiata of atrophy and white matter signal changes in NCL were first in CLN3 disease.24 One of our patients (3A) with CLN3 disease reported by Machen et al,33 expanding the findings on previously hadmildPVWMandDWMsignalabnormalityandmildsupra- reported brain MR imaging features of NCL on CT.34 To the best tentorial volume loss at 14 years of age, while the other patient (3B) of our knowledge, thalamic T2 hypointensity and periventricular was only imaged up to 7 years of age and had no discernible signal T2 hyperintense rims in infantile-onset NCL were reported by abnormality. Unfortunately, we do not have morphometric data Vanhanen et al35 for the first time in 1994. The white matter sig- on these images. nal change was hypothesized to represent loss of myelin due to White matter signal abnormalities, starting from the periven- Wallerian degeneration based on histopathologic and micro- tricular white matter with progression to deep and subcortical scopic studies.7,36-38 The thalamic T2 darkening was speculated white matter in NCL, have been reported and have been attrib- to represent accumulation of iron, though this was debated.38 uted to white matter degeneration or abnormal myelin.18,19 We Vanhanen et al14 studied postmortem MR imaging with histopa- noted a distinctive abnormality in our cohort with involvement thologic correlation in 8 patients with infantile NCL in 1995 and of the insular/subinsular region seen in 75% of our patients. To demonstrated almost complete loss of cortical neurons, axons, and the best of our knowledge, this brain MR imaging feature has not myelin sheaths in all patients, along with astrocytic proliferation been reported previously. Additionally, we identified T2/FLAIR containing periodic-acid-Schiff-positive storage material. They also hyperintensity of the PLIC and ventral pons in 91% and 79%, demonstrated loss of thalamic neurons and loss of granular and respectively, in our study cohort, which has been rarely reported Purkinje cells in the cerebellar cortex. They speculated that the tha- in the literature.17,18 Jadav et al17 reported PLIC hyperintensity as lamic T2 hypointense signal was due to accumulation of saposin an uncommon-but-characteristic brain MR imaging feature of (similar to GM2 ) and also by hypertrophic astrocytes CLN3 disease, though Holmberg et al23 also had previously containing storage protein and glial fibrillary acid protein. reported this finding in a CLN5 disease cohort. In our study, this In addition to their previous reports, Vanhanen et al,18 in was seen not only in juvenile-onset but also in infantile and late- 1995, reported progressive cerebral atrophy in infantile-onset infantile onset NCL. NCL starting from 13 months of age and peaking at 4 years of The differences in imaging phenotypes (eg, predominant cere- age, redemonstrated by the same group in 2004 in patients with bral over cerebellar atrophy and vice versa) is intriguing. As proved CLN1,20 with cerebellar atrophy lagging behind cerebral alluded to earlier, different subtypes of NCL may represent dis- atrophy. All 6 of our patients with CLN1 disease (infantile onset) tinct disorders, each with its own molecular pathway converging showed this pattern of initial early-onset cerebral atrophy fol- to a common end point (including storage of autofluorescent ma- lowed by later-onset cerebellar atrophy. terial and neuronal death). The NCL genes encode several types Patients with late infantile-onset NCL have been reported to of gene products that include lysosomal , soluble lysoso- show early-onset cerebellar atrophy.23,39,40 We also identified mal , transmembrane domain–containing proteins, and similar findings in our late-infantile-onset CLN2, CLN5, and other proteins with different subcellular localizations.1,41 The pre- CLN7 diseases, wherein most patients showed earlier onset and, cise localization and function of many of these proteins remain in most, a greater degree of cerebellar atrophy compared with elusive. However, several roles of these proteins have now been cerebral atrophy. Interestingly, this was most remarkable in our elucidated, including apoptosis and autophagy, endocytosis, ve- CLN7 disease cohort wherein 5 of 6 patients showed this finding. sicular trafficking, cell proliferation, pH homeostasis, synaptic On the other hand, both patients with CLN6 disease (early-juve- functioning, and protein secretion.1,41 Furthermore, researchers42 nile and late-infantile NCL) had a greater degree of cerebral atro- have demonstrated interaction among NCL proteins, with the phy compared with cerebellar atrophy. CLN5 protein interacting with CLN2 and CLN3 polypeptides, Juvenile NCL generally demonstrates cerebral and cerebellar at- suggesting the possibility of common pathways among these sub- rophy, usually after the ages of 9 and 13 years respectively,19 types. In a recent study, CLN1, CLN3, CLN6, and CLN8 diseases though quantitative white matter signal intensities may be abnor- have been linked to endoplasmic reticulum stress resulting in ap- mal at a younger age.19 Studies have also demonstrated progressive optosis.43 Whether the cerebral cortex is particularly susceptible hippocampal atrophy,25 altered white matter microstructure,22 and to endoplasmic reticulum stress–related apoptosis accounting for

AJNR Am J Neuroradiol :2020 www.ajnr.org 5 predominant cerebral atrophy in these subtypes is unclear but 2. Uvebrant P, Hagberg B. Neuronal ceroid lipofuscinoses in appears plausible. The pathogenesis of NCL is therefore multifac- Scandinavia: epidemiology and clinical pictures. Neuropediatrics – torial and occurs not only due to the accumulation of lipopig- 1997;28:6 8 CrossRef Medline ments but also due to mitochondrial dysfunction, endoplasmic 3. Mole SE, Williams RE, et al. Neuronal ceroid-lipofuscinoses. In: Adam MP, Ardinger HH, Pagon RA, eds. GeneReviews.Universityof reticulum stress, and alterations in cellular pH, which lead to ex- Washington, Seattle; 1993 cessive production of mitochondrial reactive oxygen species and 4. Geraets RD, Koh Sy, Hastings ML, et al. Moving towards effective disturbed calcium homeostasis, resulting in apoptosis and neuro- therapeutic strategies for neuronal ceroid lipofuscinosis. Orphanet nal loss. Each of the NCL proteins has varying effects on these JRareDis2016;11:40 CrossRef Medline cellular functions, resulting in slight differences in phenotypes 5. Mukherjee AB, Appu AP, Sadhukhan T, et al. Emerging new roles of and neuroimaging features. the and neuronal ceroid lipofuscinoses. Mol Neurodegener 2019;14:4 CrossRef Medline This study has several limitations. First, because it was a retro- 6. Kline RA, Wishart TM, Mills K, et al. Applying modern Omic tech- spective study, MR imaging performed in different machines and nologies to the neuronal ceroid lipofuscinoses. Biochim Biophys protocols was analyzed, with nonuniform imaging parameters. Acta Mol Basis Dis 2020;1866:165498 CrossRef Medline Second, because images were analyzed during a 30-year period, 7. di Ronza A, Bajaj L, Sharma J, et al. CLN8 is an endoplasmic reticu- there was an insufficient number of cases with the data required to lum cargo receptor that regulates lysosome biogenesis. Nat Cell – perform meaningful quantitative analyses. We, therefore, restricted Biol 2018;20:1370 77 CrossRef Medline the study to qualitative analysis of signal intensity and volume loss. 8. Cooper JD, Mole SE. Future perspectives: what lies ahead for neu- ronal ceroid lipofuscinosis research? Biochim Biophys Acta Mol Third, only 9 patients had follow-up imaging, making it difficult to Basis Dis 2020;866:165681 CrossRef Medline assess progression of disease. Last, there was under-representation 9. Kohlschütter A, Schulz A, Bartsch U, et al. Current and emerging of certain subtypes (eg, CLN3 disease) in this study cohort. treatment strategies for neuronal ceroid lipofuscinoses. CNS Drugs 2019;33:315–25 CrossRef Medline CONCLUSIONS 10. Gene Therapy for Children with CLN3 . ClinicalTrials. gov. Accessed May 7, 2020 CLN1 and CLN7 diseases were the most common subgroups in 11. Gene Therapy for Children with Variant Late Infantile Neuronal our study cohort. The difference in the median time from disease Ceroid Lipofuscinosis 6 (vLINCL6). ClinicalTrials.gov.Accessed onset and diagnosis was 1.5 years. Given recent FDA approval of May 7, 2020 the use of cerliponase alfa for treatment of CLN2 disease and 12. D’Incerti L. MRI in neuronal ceroid lipofuscinosis. Neurol Sci – ongoing phase I/IIa clinical trials with gene therapy for CLN3 2000;21:S71 73 CrossRef Medline and CLN6 diseases, it is imperative to reduce this time gap to 13. Baker EH, Levin SW, Zhang Z, et al. MRI brain volume measurements in infantile neuronal ceroid lipofuscinosis. AJNR Am J Neuroradiol arrest disease progression. In patients with a history of develop- 2017;38:376–82 CrossRef Medline mental regression, brain MR imaging and referral to a neurologist 14. Vanhanen SL, Raininko R, Santavuor P, et al. MRI evaluation of the and geneticist are crucial to diagnose patients at the disease onset. brain in infantile neuronal ceroid-lipofuscinosis, Part 1: postmortem We identified reported classic neuroimaging features in all MRI with histopathologic correlation. JChildNeurol1995;10:438–43 except 1 patient with NCL in our study, including predominant CrossRef Medline cerebellar-over-cerebral atrophy in CLN2, CLN5, and CLN7 dis- 15. Jiangxi X, Li G, Yuanchun Z, et al. MRI findings in childhood with neu- ronal ceroid lipofuscinosis. Chinese Journal of Radiology 2003;37:802–04 eases and minimal abnormality up to early adolescence in CLN3 16. Peña JA, Cruz EM, Leendertz R, et al. MRI and proton spectroscopy disease. We confirmed less frequently reported findings of abnor- in children with late infantile neuronal ceroid lipofuscinosis: pre- mal signal intensity in the deep white matter, posterior limb of liminary results. J Pediatr Neurol 2015;05:215–20 CrossRef the internal capsule, and ventral pons and demonstrated that 17. Jadav RH, Sinha S, Yasha TC, et al. Magnetic resonance imaging in these findings are more common than previously reported in the neuronal ceroid lipofuscinosis and its subtypes. Neuroradiol J – literature. We report abnormal signal intensity in the insular/sub- 2012;25:755 61 CrossRef Medline insular region for the first time. 18. Vanhanen SL, Raininko R, Autti T, et al. MRI evaluation of the brain in infantile neuronal ceroid-lipofuscinosis, Part 2: MRI find- ings in 21 patients. J Child Neurol 1995;10:444–50 CrossRef Medline ACKNOWLEDGMENTS 19. Autti T, Raininko R, Vanhanen SL, et al. MRI of neuronal ceroid lip- A.B. is partially funded by Ontasian Imaging Laboratory (OIL), ofuscinosis. I: cranial MRI of 30 patients with juvenile neuronal ce- – Toronto. roid lipofuscinosis. Neuroradiology 1996;38:476 82 CrossRef 20. Vanhanen SL, Puranen J, Autti T, et al. Neuroradiological findings (MRS, MRI, SPECT) in infantile neuronal ceroid-lipofuscinosis — Disclosures: Saadet Mercimek-Andrews UNRELATED: Board Membership: (infantile CLN1) at different stages of the disease. Neuropediatrics Recordati, BioMarin advisor; Consultancy: Canadian Medical Protective Association 2004;35:27–35 CrossRef Medline expert reviewer, Borden Ladner Gervais expert reviewer; Grants/Grants Pending: Physician Services Incorporation grant*; Payment for Lectures Including Service on 21. Dyke J, Sondhi D, Voss H, et al. Brain region specific degeneration Speakers Bureaus: BioMarin, Recordati. Manohar Shroff—RELATED: Other:BioMarin, with disease progression in late infantile neuronal ceroid lipofusci- Comments: I received a one-time honorarium (November 2019) for participating in nosis (CLN2 disease). AJNR Am J Neuroradiol 2016;37:1160–69 an afternoon discussion on CLN2 hosted by BioMarin, which manufactures an CrossRef Medline -replacement treatment for CLN2. 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